Ira Cooper <ira@wakeful.net> reports:

Problem: Samba is being existential.  It is wondering if it exists far too
much, especially when it can just poke itself and see.

As far as how often it does this check: I've seen it be over 50% of the calls
to this function.  Given the price of the calls involved, seems like a cheap
optimization.

------------------------------------
jra asked:
    Do you have any idea on how many calls it saves,
    and what help the optimization gives ?


As far as calls: Not 100% sure, dtrace pointed the issue out to me, and when I
saw 10-50%(Or more), I looked for an easy fix.

The real expense here is the fnctl locks on the database.  That's pretty
painful.  1000ns per call, and probably 3-4 calls in that chain.  So it doesn't
take much to come out ahead was my math.